1. Field of the Invention
This invention relates to the field of preparing aminonitriles, and more specifically relates to the field of preparing aminonitriles from a ketone, ammonia and hydrogen cyanide.
2. Description of the Related Art
The preparation of aminonitriles by combining, in some manner, the chemical equivalents of a ketone, ammonia, and hydrogen cyanide (HCN) has been performed since Strecker reacted acetone with ammonium cyanide in 1850 to produce acetone aminonitrile. In another process for preparing the acetone aminonitrile, the ammonium cyanide of Strecker is replaced with ammonium chloride and potassium cyanide. The literature is replete with examples of some variation of these procedures that are used to prepare the aminonitriles of various ketones. However, these methods are impractical for commercial operation because the raw materials used in those methods, such as ammonium chloride and potassium cyanide, are much more expensive than other raw materials, such as ammonia and HCN.
A process for preparing an aminonitrile by combining a ketone, ammonia and hydrogen cyanide is disclosed in Czech Patent No. 233,428 which issued on Mar. 14, 1985 to Vesela et al. wherein the aminonitrile is made in a two-step process by first reacting acetone and HCN to form acetone cyanohydrin, and then adding ammonia to the acetone cyanohydrin in an organic solvent. The mixture of acetone cyanohydrin and ammonia in the organic solvent is allowed to sit for two days at room temperature, at which time it produces an 89% yield of acetone aminonitrile.
In a variation of the second step of this two step process, Czech Patent No. 231,245 which issued on Oct. 15, 1984 to Vesela et al. teaches reacting acetone cyanohydrin with ammonia in an autoclave at 65.degree. C. to obtain a 92% yield of acetone aminonitrile.
The general sequence for preparing an aminonitrile from a ketone, ammonia, and hydrogen cyanide in a two step process is illustrated as follows: ##STR1## where the ketone is: acetone: R.sup.1 .dbd.R.sup.2 .dbd.CH.sub.3 --
methylethylketone: R.sup.1 .dbd.CH.sub.3 -- and R.sup.2 .dbd.CH.sub.3 CH.sub.2 -- PA1 methyisobutylketone: R.sup.1 .dbd.CH.sub.3 -- and R.sup.2 .dbd.(CH.sub.3).sub.2 CHCH-- PA1 cyclohexanone: R.sup.1 and R.sup.2 together ##STR2## PA1 methylethylketone: R.sup.1 .dbd.CH.sub.3 -- and R.sup.2 .dbd.CH.sub.3 CH.sub.2 -- PA1 methyisobutylketone: R.sup.1 .dbd.CH.sub.3 -- and R.sup.2 .dbd.(CH.sub.3).sub.2 CHCH-- PA1 cyclohexanone: R.sup.1 and R.sup.2 together ##STR4##
This two step method for preparing an aminonitrile from a ketone, ammonia, and hydrogen cyanide is undesirable for several reasons. First, the process requires an intermediate step, namely the preparation of the cyanohydrin. Secondly, the reaction between the ammonia and the cyanohydrin is very slow, and requires long reaction times. Thirdly, the aminonitrile product obtained from this process includes impurities which may be detrimental in utilizing the aminonitrile in subsequent processes.